I got the error message “unknown filesystem type vboxsf” while I was trying to share a directory from my Windows XP host to Ubuntu Interpid Ibex (8.10). In almost every where it said to install Guest additions. After spending few hours I found the solution. So decided to share with you for reference.

Step 1: Install host additions (usually you install them when you install virualbox).

Step 2: If you have created a new machine, then create a shared directory/folder. (From the machine’s Devices menu)

Step 3: From machine’s Devices menu, select “Install guest additions”

Step 4: Now in the guest (Ubuntu Ibex Interpid for my case), fire up a console and type the following:

It should install the additions.

Step 5: Now create a directory where you want to mount your shared drive. For example I have created shared directory under mount using following:

Step 6: Mount using following command:

Note that shared was the name of the directory I shared from virtual box and /media/shared is the directory where I wanted to mount my shared directory.

Now you should be able to see the files under shared directory in both system.

Enjoy!